In recent years, a drug coating was coated onto the stent implanted in the body so as to avoid the incidence of in-stent restenosis after interventional treatment. Drugs mostly carried by currently used drug-eluting stents are those for inhibiting intimal hyperplasia or tunica media hyperplasia, including rapamycin, paclitaxel and derivatives thereof, etc. When the stent carrying above-mentioned drug is implanted into a human body, the stent will continuously release the drug for inhibiting intimal hyperplasia or tunica media hyperplasia into vessel wall to reduce the occurrence rate of in-stent restenosis.
Studies have shown that vascular restenosis formation is not only related to intimal hyperplasia or tunica media hyperplasia after vascular injury, but also related to vascular remodelling. Vascular remodeling is the main factor for in-stent restenosis, accounting for 70% possible causes of restenosis, while intimal hyperplasia or tunica media hyperplasia accounts for only 30% possible causes of restenosis.
Therefore, the current drug-eluting stents for inhibiting intimal hyperplasia or tunica media hyperplasia can not reduce the incidence of in-stent restenosis to the greatest extent. In addition, the current drugs for inhibiting intimal hyperplasia or tunica media hyperplasia, such as rapamycin, paclitaxel and derivatives thereof, may suppress endothelial cell growth, and delay vascular endothelialisation. The problem that blood vessels can not be completely endothelialized may cause late thrombosis.